Making a rocket stove (versus a mass heater)

So I read the mother earth news article, bought and read Kiko's book, found some very helpful material online from Sigi Koko, bought these plans... and am still unsure about a few things. I grew up in suburbia and don't have the first idea about wood stoves. I plan to put a roof over my outdoor kitchen (including the oven) at some later date. For now I'll cover the oven with a tarp when it rains. What do I need to get the stove pipe through the roof? Let's assume it's a tin roof on a wooden support structure. I might have access to an old billboard vinyl, but expect that would be even more difficult to reconcile with the stove pipe. Can I buy an inexpensive 6" single-wall pipe to build in for now and cut it off and splice on something else later if I need to? Why are the double and triple wall stove pipes so expensive? would it be less expensive to use metal supports under the tin roofing? Would I still need to use special pipe through the roof?
If you actually see this and actually reply... can you also direct me to where I can learn about the critical components/dimentions of a rocket *STOVE*? Not a mass heater, just a stove. Google... youtube... Permies... doesn't matter where I search for rocket *stove* I always end up with information on mass heaters instead. I just want to be able to can tomatoes outside, not heat a house!

Rachel, I pulled your question from the discussion of Erica's pizza oven plans because I know there's good stuff here at permies.com about rocket stoves. One of the projects for the event at Wheaton Labs (soon!) is to make a rocket stove powered canning kitchen on a skiddable sled. I think that's in the second weekend, which can be attended as a stand alone event.